Address lines scrambled on a '99 Saturn

[sabercatpuck]

This seemed a good place to put this in case anyone else ever runs into this. On the Saturn that I am working on there are several pairs of address lines that get mixed up going to the flash (68HC11F1 CPU and 29F010 flash). I ended up having to build a special chip carrier to properly descramble the address lines before reading it through the Willem. I have a different topic out there for actually talking about the assembly code, but thought that just in case someone else was getting wierd data out of their flash they might try ohming out the address and data lines to make sure they were actually connected A0-A0 A1-A1, etc

[sabercatpuck]

I finally designed a pcb to be etched. This will plug into the ziff socket on my willem programmer and go to a plcc32 socket. I left the lines going to points that I could then solder wire from one pin to another as needed since in my case the address lines need to be unscrambled before being read out correctly. I hear that I can use inkjet photo paper in a laser printer to print out the traces, then use an iron to transfer them onto the copper board and etch. Been awhile since I did this so hopefully it goes well (last time I etched a board I used a resist pen to freform draw the thing on the copper).

[sabercatpuck]

Akk, went downstars to do some work and remembered that this needs to be a mirror image because when you transfer it back to the copper it will get reversed. After playing around I think I got it corrected, first I had to flip it, then it decided to make the resolution 75x75 again so I had to hex edit the file to get that back to the 306x306 that I needed to make it print right since as near as I can tell there is no easy way to set the resolution in paint (why not I have no idea). For the record you set in the bmp file,use a hex editor and it is right near the beginning in the headder, h26 and h2A to 0f and h27 and h2B to 2F ($2f07 = 12039, 12039/39.37 inches/meter = 305.7 DPI).
Oh and for more info on the transfer method you can check this out: http://www.mrdwab.com/john/How-to-make-PCBs.html

[sabercatpuck]

There is more good info on PCB etching and etchants available on this site.
http://www.instructables.com/id/Stop-us ... etter-etc/

Apparently you can recharge many etchants by just adding oxygen back into the mix, and the waxy shiny paper found in magazines can be used with better resullts for transfering toner resists to the board.

I do recomend looking around the site above, there are many interesting tips and tricks if you are interested in trying to make your own PCB's.

[Holden202T]

as a reasonably new comer to etching i can say that it is quite rewarding making your own pcbs!